Method of sizing carbonate filled paper



Patent ed May 5, 1931 j UNITED STATES PATENT OFFICE HAROLD ROBERTRAPTOR, OF LAWREIICE, SETTS ,ASSIGNOR TO RAFFOLD PROCESS CORPORATION, ACORPORATION 01 MASSACHUSETTS ployed in the METHOD OF SIZING CAR-BONATEFILLEDPAPER No Drawing.

This invention relates to the manufacture of paper and more particularlyto an improved method of sizing carbonate filler. v q a A principalobject of'this invention is to provide a method of sizing paper filledwith carbonate filler wherein paraifin is employed as the sizing agent,the parafiin being emform'of a substantially nonbreakable emulsion, thedisperse phase of such emulsion being concentrated by the mutualprecipitation or flocculation of two suitable precipitating agents inthe presence of the emulsion at the wet end of the paper machine,

Other objects and advantages of this-in- Vention will become apparentduring the course of the following description.

In my copending application Serial No. 304,170, filed Sept. 5, 1928, Ihave described a process of sizing carbonate filled paper wherein asubstantiallynonbreakable paraffin emulsion is employed as the sizingagent-,-

the disperse phase of such emulsionbeing concentrated by the mutualprecipitation of two precipitating agents such as sodium resinate andalum at an earl stagein the paper making process, and w erein-the sizingeffect'of the sizing agent which is wholly or in part-deteriorated b theaction of the carbonate filler employe is restored by' the subsequentaddition to the suitable sizing restoring agent, such as alum. I havenow discovered that a certain satisfactory measure of success can beobtained by omitting the addition of one ofthe mutual precipitatingagents 'suchas alum at an early stage of the process and adding it tothe paper mix at the wet end of the paper machine.

In the preferred'practice of-my process I add to fibrous material in abeater, mixer, or similar device carbonate filler, a substantial- 1ys-nonbreakable paraflin emulsion and so- .3 dium ires1nate 1n asufliclent amount as 1nd1-' 5:" cated below. Other material such ascolor-' fling matter-may be added to the mix if de- 5 sired. The mix: isthen passed through the ,5 i"'f u's ual preliminary steps in the papermaking :and a or subsequent to the point .wherethe mix is diluted priorto its. passage paper filled with paper mix of a Application filedSeptember 5', was, Serial no. 304,173.

on to a web-forming device of a paper machine,

a'suitable amount of a mutual precipitating agentsuch as alum,preferably in solution, is'added to the mix, preferably con-,

tinuously. In other words, this material is added to the mix at the wetend of the paper machine. This results in :the concentration of thedisperse phase of the parafiin emulsion and the afiixing of suchdisperse phase to the fibers whereb the pa er, but would produce asubstantially unslze paper. Thus the precipitate produced by sodiumresinate and alum does not in this case act as a sizing agent but as aconcentrating. agcnt.- Of course I may, if I desire, use a greaterquantity of sodium resinate, but it-is to be pointed out that it ispossible to A secure satisfactory sizin by my .process where there isnot enoug sodium resinate used to'impart sizing of itself.

' By the addition of one of the mutually precipitating materials, suchas the alum, at the wet end of the paper machine, the alum is I after"the passage of the mix. through the usual felting and finishing steps,

thus aded at a point where there will be a minimum of intimacy and timeof contact of the constituents of the mix, before the paper web isformed. It is necessary as indicated to add the alum at or subsequent tothe point of dilution of the mix, as I have found that if it be addedwhen the mix is in relatively concentrated condition and particularlywhen 'the relatively concentrated mix is subjected-to agitation as isnormal-in stock chests, the sizing effect in the mix is very quicklydeteriorated even to the point of complete destruction. The sizingeffect even when the mix is in the diluted condition is graduallydeteriorated, but is substantially u'naifected"within the time limitsthat the mix is maintained in the dilute state in the usual paper-makingprocedure. Moreover, althoughagitation in the dilute state hastens to acertain extent the dete rioration of the sizing effect, the speed ofdeterioration is not nearly so pronounced asr ments do not indicate thatany substantially better sizing effect is obtained thereby, although thetendency to foam may be somewhat lessened, and such addition thereforecan be considered the substantial equivalent of adding sodium resinatein the beater.

Similarly of course it is obvious that the substantially nonbreakableemulsion maybeadded at any point prior to web formation other than inthe beater, even after the ad dition of the alum, and suchaddition-therefore can be considered the substantial equivalent ofadding the substantially nonbreakable emulsion in the beater, providingonly of course that the substantially non'breakable emulsion must bepresent at the time when the sodium resinate and alum mutuallyprecipitate so that its disperse phase may be concentrated thereby aspreviously described herein. v The alum'solutionneed not be addeddirectly to the fibrous mix, but can be added to the fresh water orwhite water, e. g. tray water, with which the mixis diluted. If the alumbe added to the tray water, time interval should elapse before the sotreated tray water is used for dilution Although substantially more foamis produced inthe herein described process than in the process referredto in my copendmg application, (except possibly in that-modificationwherein sodium resinate would be added at the wet end of the papermachine after the alum addition), nevertheless the foam is altered incharacter by the alum before the mix is passed onto the web formingdevice, so that what foam is not held back in the rifllersorthe like isof such nature that it causes substantially no trouble during theformation of the web, and the paper produced by this process is of asatisfactory quality. Moreover inasmuch as the amount of alum used inthe present process is less than that used in the process set forth inmy copending application referred to above, the present processtherefore results in a more economical operation.

The substantially nonbreakable paraffin emulsion herein described shouldnot be confused with parafiin emulsions prepared by employing asaponaceous emulsifying agent.

only a brief Nor shouldthe emulsion be confused with emulsions made withan insoluble emulsify- 1ng agent such as colloidal clay, such forexample as emulsions produoed from 'pitchy or bituminous materials suchas tar or asphalt. These various types of emulsions re-' ferred todiffer in many respects from my substantially nonbreakable paraflinemulsion and are not suitable for use in the practice of my process.

The paraflin emulsions which I have found to be substantiallynonbreakable by any of the chemical or mechanical agencies ordinarilyemployed in paper making'in the con centrations or intensities at whichthey are normally used may be made in a variety of ways, for instance,with gums such as gum ghatti or gum arabic. While dextrin of itself doesnot appear to be suitable as an emulsifying' agent, particularly if theemulsion is to be stored for any appreciable time, it does howeverappear to be useful in connection with the gums mentioned above. As thegums are normally much more expensive than (lextrin, thedextrin may thusbe used in conjunction with the gums to produce in general 'a lower costemulsion. I have tested several formulae involving the use of gums anddextrin whichgive emulsions of essentially the nature desired, and whichappear to work satisfactorily for the purpose. However, the one which Iprefer to use in practice and which I have found to work Well-on apractical scale, is an emulsion made of paraffin with gum ghatti anddext'rin as emulsifying agents. In one such emulsion, for example, whichproved satisfactory, I used by weight as follows:

15 parts parafiin, 1 part gum ghatti, 1 part dextrin, 83 parts Water.

As stated above so far as I have been able to discover by experiment,the'emulsions which I employ are not affected in anyway by any of thechemicals with which they come in contact at the concentrations at whichthey are used in the paper making process, nor are they'aifected by anyof the mechanical agencies with which they come in contact at theintensities at which they are normally-employed in the paper makingprocess.

The reason for this latter characteristic is probably that the particlesin my emulsions are surrounded with a film which is one or moremolecules in thickness and hence'entire- 1y of negligible thicknesscompared with any insoluble emulsifier film. Hence such films cannot beknocked oil or ruptured by ordinary mechanical means, as the thicknessof this film is of entirely different order of magnitude (smaller) thanare the clearances which ob --tain in the paper makingmachinery.

Of course it is not necessary that the emulsifier I use be water solublein-the sense that sodium chloride, for instance, is soluble, asmaterials which are known in the art as bepable of having its dispersephase concen-' ing colloidally soluble, are also suitable. For

example gum ghatti which is suitable for my use may be considered to bein a measure col loidally soluble. With emulsifiers of the type I employthe condition of the layer surrounding the disperse phase .is such thatby mechanical action in the paper making process,

. this layer is not disrupted, and therefore, the

emulsion remains substantially nonbreakable as heretofore indicated. Itis to be understood that I do not confine myself to the materialsindicated aboveas being suitable for my emulsion since now that theprinciple of the use of a substantially nonbreakable parafiin emulsionwhich is catrated has been established in the paper industry, doubtlessother similar emulsions will v emulsion nor to definite proportions ofemulbe evolved. N or'do I confine myself to the definite concentrationof the paraffin in'the sifying agents to each other or to the parai'fimjas these may be variedin considerable degree without affecting thedesirable qualities of the emulsion.

Emulsions of the character referred to may- Y be made ina variety ofways, as for example,

in a dispersion machine such as any of a number of colloid mills orhomogenizers. A suitable way is to melt the paraflin, dissolve. theemulsifying-agent or agents in water, heat the emulsifying agentsolution above the melting point of the parafiin and then feed themelted paraflin and the heated solution of emulsifying agents jointly tothe emulsifying machine. I p

' In regard to the paraffin used, it 1s to be understood that either lowor high melting point material can be employed. The" so-calledfullyrefined parafiin is entirely satisfactory sinceit does not impartobjectionable color to white sheets. However, for purposes ofeconomy, itis often desirable to use a less pure material such for example asthematerial which is commonly known to theTtrade as semi-refinedparaifinscale, containing approximately 1-2 per cent of oil'and water asimpurities, which material gives satisfactory results. Such materialwill perhaps in certain cases have varying melting points, but oneparticular sample used, for example, had a melting point ofapprox1mately 115 F.

(46 (3.). Other even more impureparafa fins may be 1 used, especially ifthe color (whiteness), requirements of the finished paper are not tooexacting, or if papers, other than white, are to be In de.

As heretofore stated, in the preferred practice of my process I add atthe wet end of the paper machine to'a mix containing fibrous materialsbdium'resinate and a substantially nonbreakable parafiin emulsion ofthe char- :acter referred to, a material which will mutually precipitateor flocculate with the sodium resinatepresent in the IPIX. This; resultsin 'vantageonslyfied' in the' the concentration of the disperse phase of"j the parafiin emulsion whereby such disperse phase becomes attached tothe fibers and does not filter 'oif therefrom during the passa e of themix over the web-forming device 0% paper machine. The mutualprecipitation or flocculation described serves, as stated, as a meansfor concentrating the disperse phase of the emulsion without breakingthe emulsion,

the disperse phase in the: meantime being maintained in emulsifiedcondition, and substantially nonbreakable by chemical or mechanicalmeans; This concentration of the disperse phase appears toproduce acomplex wh1ch expenments lndicate to be an lntermediate between atrueemulsion and a re-.

solved or broken emulsion. For example, the complex can be temporarilydispersed by mechanical means but not diluted in the true sense as inthe case of true emulsions. However, the complex can in a sense bediluted by dissolving .the precipitate of the mutually flocculatingagents therein and reconverting to atrue emulsion. Thus while it isclear that the complex is not a true emulsion it is on the other hand,not a resolved emulsion.

For example, the parafiin is not present in the concentrate asindividual unitary deposited particles of paraflin, but rather inemulsified form, each particle being surrounded by a layer or film ofemulsifying agent which prevents the individual particles from havingcontact not only. with other particles of paraflin, but also from havingcontact with either the alum-sodium resinate precipitate,

the.

or the fibres, or other constituents of the fibrous mix. .The existenceof the parafiin able paraflin emulsion Calcium; carbonate magnesiumhydroxide (carbonate er J M aterz'dl, added proportionately and contin-UKOUS'ZQ/ 0a dilution Pound- Another illustrative furnish is as follows:

Material added in the beater Fibrous furnish (e. g. approximately equalparts of 'sulphite, soda and old paper stocks) Rosin (added in the formof sodium resinate)I Parafiin (added in the form of substantiallynonbreak- Pounds lie sulphite and soda Dulps) 17%)8 able paraifinemulsion) z 30 Broke" (containing calcium carbonate magnesium hydroxide(carbonate fil1er)) 170 Oaaium carbonate magnesium L HrBETEETCERBBTEE op Alum a In the above formulae, the weightsof car'- bonate filler referto the bone dry basis, the weights of all other ingredients being givenon the air dry basis.

In either of thabove furnishes starch may be used. It may beconveniently added to the beater subsequent to the addition of thecarbonate filler, or otherwise if desired. Suitable coloring matter maybe added if desired.

The illustrative furnishes given above produce satisfactorily sizedpaper, and, as will'be apparent, the sizing can be increased 'ordecreased by varying the relative quantities of the materials used inthe above formulae. The resultant paper may be used for such purposes asthose to which sized papers are normally put including that as a rawstock for further conversion as for example for coatmg.

In place of alum in the practice of my process I may employ with ameasure of success an acid such as sulfuric acid (H SO an acid salt suchas sodium bisulfate (NaIIsOior a salt of a trivalent metal, such asferric iron, or the other salts of aluminum. Of the aluminum saltsavailable I may use the chloride or the like, but I prefer to useordinary alum. i

In place of sodium resinate I may use satisfactorily in the practice ofmy process other soaps, such as the oleat'es, or any partially orcompletely saponified material, such as saponified beeswax.

, 'Bythe term carbonate filler?-'as employed herein, is intended to beincluded calcium carbonate, of which lime mud from the causticizingprocess is one form; calcium carbonate magnesium basic carbonateemployed in the paper disclosed, in m U. S. Patent No. 1,595,416;calcium carbonate magnesium hydroxide disclosed in my U. S. Patent No.1,415,391; or other substantially water insoluble normal or basiccarbonates of alkaline earth metals, (which expression is hereinintended to includcmngnesium) ,or compounds,

double salts, or physically associated mixtures of these with one ormore other acid soluble materials of a substantially'water insolublenature. The term carbonatefiller is also intended to include fibrousmaterial and/or other material such as paper coating constituents or thelike containing one or more compounds of the character referred to, suchas old papers or slmilar papers,

" broke, or the like.

By. ,the term Wet end of the paper machine is interidedto beincludedthose instrugtrated paper mixis diluted, and7treated, conve'yedor fed up to the point of web-formation, such as the mixing box,regulating and proporti'oning devices, rifliers, troughs, screens, headboxes, inlets, and the like, including also instrumentalities used inthe white water cycle.

When I employ the term paraffin herein, I mean parafiin wax, which 1ssolid at ordinary or room temperature. I do not mean to restrict myselfonly to the paraflin hydrocarbons, but mean to include in this term allthe hydrocarbons of -a waxy nature sub-- stantially unsaponifiable andinert to acidic and alkaline materials under ordinary conditions oftemperature and pressure, whether derived from petroleum, shale,lignite, earth wax, or other natural or artificial sources.

I do not, however, means to include in this term material of a, pitchynature, such as bitu: men or asphalt.

Where I use the term sodium resinate it is to be understood that I meanit to include any material produced by the action of alkali, generallyin aqueous solution, on rosin, or on natural or synthetic resin acid oracids, regardless of the exact composition of the product, or thevarying composition which different samples may possess.

When I use the word paper herein, I use it in the broad sense to includeproducts of manufacture of all types and of all weights and thicknesses,which contain as an essential constituent a considerable amount ofprepared fiberand which are capable of being produced on a Fourdrinier,cylinder, or other forming, felting, shaping or molding machine.

While I have described in detail the preferred embodiment of myinvention, it is to be understood that the details of procedure, theproportionsof ingredients, and the arrangement of steps may be widelyvaried without departing from the spirit of the invention or the scopeof the subjoined claims.

I claim:

1. The method of. manufacturing a sized paper filled with carbonatefiller comprising adding to fibrous material a substantiallynonbreakable paraffin emulsion and a substance which will react with asecond substance subsequently to be added to form a precipitate, saidreaction serving to concentrate the disperse phase of said parafiinemulsion but not to break said emulsion, adding carbonate filler,thereafter adding said second precipitating substance under conditionsfavoring the minimizing of the time of contact of the constituents ofthe mix, and thereafter making paper therefrom.

2. The method of manufacturing a sized paper filled with carbonatefiller comprising adding to fibrous material a substantiallynonbreakable paraffin, emulsion and a substance capable of reacting witha second substance subsequently to be added to form a precipitate uponthe fibrous material, said reaction serving to concentrate inassociation with saidpreclpitate thedisperse phase of said paraflinemulsion but not to break said emulsion, said precipitate beingsubstantially incapable of having the paraflin associated therewithreleased from emulsified condition by mechanical means, adding carbonatefiller, thereafter adding said secondprecipitating substance underconditions favorin the minimizing of the time of contact of theconstituents of the mix, and thereafter making paper therefrom.

3. The method of manufacturing a sized paper filled with carbonatefiller comprising adding to fibrous material asubstantially nonbreakableparaffin emulsion and a substance which will react with a salt of atrivalent metal to form a precipitate, said reaction serving toconcentrate the disperse phase of said paraffin emulsion but not tobreaksaid emulsion, adding carbonate filler, thereafter adding said saltof a trivalent metal under conditions favorin the minimizing ofthe timeof contact 0 the constituents of the mix, and thereafter making papertherefrom. 4. The method of manufacturing a sized piper filled withcarbonate filler comprising a ing to fibrous material. a substantiallynonbreakable paraflin' emulsion and a substance which will react with asalt of aluminum to form a precipitate, said reaction serving toconcentrate the disperse phase of saidparaflin emulsion but not to breaksaid emulsion, adding carbonate filler, thereafter adding'saidsalt ofaluminum under conditions favorin the minimizing of the time of contactof t e constituents of the mix, and thereafter making paper therefrom.

- 40 5. The method of manufacturing a sized paper filled with'CarbonateTfilier comprising ad ing to fibrous material a" substantiallynonbreakable 'paraifin emulsion and a substance which will react'withalum to' form a precipitate, said reaction servin to concentrate thedisperse phase, of sai parafiin emulsion but not to break said emulsion,add- -ing carbonate filler, thereafter adding said alum under conditionsfavoring the minimize 0 ing of the time of contact of the constituentsof {the mix, and thereafter 'makin'gi paper therefrom. v

6. The method of manufacturinga sized paper filled with carbonate fillercomprising s adding to fibrous material {a substantially I nonbreakableparafiin emulsion and a substance which will react with a second sub:stance subsequently to be added to form a precipitate,.said reactionserving to concentrate 0 the disperse phase of said paraflin emulsionbut not to break said emulsion, adding carbonate filler, thereafteradding said second precipitating substance under conditions favoring theminimizing of the t me and 1ntimacypf contact of the constituents of;the

mix, and thereafter making paper therefrom. 7. The method ofmanufacturing a sized paper'filled with carbonate fillerl comprisingadding to fibrous material a substantially nonbreakable paraflinemulsion and a substance which will react with a second substancesubsequently-to be added to. form a precipitate, said reaction servingto concentrate the disperse phase of said parafiin emulsion but not tobreak said emulsion, adding carbonate filler, thereafter adding saidsecond precipitating substance at the wet end of the paper machine, andthereafter makingv paper therefrom.v

v 8. The method of manufacturing a sized paper filled with carbonatefiller comprising adding .to' fibrous material asubstantiallynonbreakable paraffin emulsion and a substance which willreact with a second substance subsequently to be added to form aprecipitate, said reaction serving to concentrate the disperse phase ofsaid parafiin emulsion but not to break said emulsion, adding carbonatefiller, thereafter adding said sec- 0nd precipitating substance at apoint in the process at which the mix is diluted preparatory to use on aweb-formin device, and thereafter making paper there rom.

9. The method of manufacturing'a sized paper filled with carbonatefiller comprising ing a precipitant for said saponified mate-' rial atthe wet end of ,the paper machine, and

thereafter making paper therefrom.

11. The method of manufacturing a sized paper filled with carbonatefiller comprising mixing with fibrous material a substantiallynonbreakable paraflin emulsion,

ingalum at the wet end ofthe paper machine,

thereafter making paper therefrom 12. The' method'of manufacturing asized paper filled with carbonate filler comprising mixing with fibrousmaterial a substantially nonbreakable paralfin' emulsion, soap, andcarbonate filler, thereafter adding alum at the wet after making papertherefrom.

passing the mixsa' onifiedmaterial, and carbonate filler',-thereaf "raddend of the paper machine, andthere-- 13. The method of manufacturinga sized paper filled with carbonate 'fill'er comprising mixing withfibrous material a substantially nonbreakable paraflin emulsiomsodiumresinate, and carbonate filler, thereafter adding alum at the wet end ofthe paper machine, and thereafter making paper therefrom.

14. The method of manufacturing a sized paper filled with carbonatefiller comprising mixing with fibrous material a substantiallynonbreakable paraflin emulsion, sodium resinate, and carbonate filler,thereafter adding a precipitant for said sodium resinate at the wet end(if the paper machine, and thereafter making paper therefrom.

15. The method .of manufacturing sized paper filled with carbonatefiller comprising mixing with fibrous-material a substantiallynonbreakable parafiin emulsion, sodium resinate in an amountinsufficient of itself to impart a substantial degree of sizing to the*paper, and carbonate filler, thereafter adding alum at the wet end ofthe paper ma- Ichine, and thereafter making paper-therefromr 16; Themethod of manufacturing'a slzed' paper filled with carbonate fillercomprising mixing with fibrous material a parafiin emulsion made withgum ghatti as emulsifying agent, sodium resinate, and carbonate filler,thereafter adding alum at the wet end of the papa: machine, andthereafter making paper therefrom. v

17. The method of manufacturing a sized paper filled with carbonatefiller comprising mixing with fibrous material a paraffin emulsion madewith gum ghatti and dextrin as emulsifying agents, sodium resinate, andcarbonate filler, thereafter adding alum at'the wet end of the papermachine, and thereafter makin paper therefrom. i

18. n a method of manufacturing a sized paper filled with carbonatefiller, the step of adding at the wet end of the paper machine aprecipitant to a paper mix containing fibrous material, carbonatefiller, a substantially nonbreakabl e p'araflin emulsion and vsaponified material.

' Y of adding at the wetendof the paper manonbreakable 19. In a methodof: manufacturing a sized paper filled with carbonate filler, the. stepchine, asalt of a trivalent metal to a paper mix containing fibrousmaterial, carbonate filler, a substantially nonbreakable paraflinemulsion and saponified material.

20. In a method of manufacturing a sized paperfilled with carbonatefiller, the-step of'adding at the wet end of the paper machine a salt ofaluminun'rto a paper mix containing fibrous material, carbonate filler,a substantially rionbreakable paraflin emulsion and sa onified material.

inate.

24. That step in the method of manufacpaper filled with carbonatefiller, the ste of adding at the wet end of the paper mac ine alum to apaper mix containing fibrous material, carbonate filler, a substantiallynonbreakable paraffin emulsion and soap.

. 23. In a method of manufacturing a sized paper filled with carbonatefiller, the step. of adding at the wet end of the paper machine alum toa paper mix containing fibrous material, carbonate filler, asubstantially nonbreakable paralfin emulsion and sodium resturing asized paper filled with carbonate filler in which a parafiin emulsion isemployed, comprising the addition of aprecipitatin substance'to thepaper mix at the wet end 0 the paper machine.

25. That step in the method of manufac turing a sized paper filled withcarbonate.

filler in which a paraflin emulsion is employed, comprising the additionof acidic material to the paper mix at the wet end of i the papermachine.

26. hat step in the method of manufacturing a sized paper filled withcarbonate filler in which aparaflin emulsion is employed, comprising theaddition of metallic salt to the paper mix at the wet-end'of the.

21. n a'method of manufacturing a sized paper filled with carbonatefiller, the step of adding at the wet end of the paper machine alum; toa paper mix containing fibrous material, carbonate filler, asubstantially fied material.

22. In a method of manufacturing a.

paraflin emulsion and saponiature. I

